FOR more than a year, the Museum of Fine Arts, Boston, has endured criticism for lending a collection of Monet paintings to a profit-making gallery on the Las Vegas Strip.

The museum, which has shared in millions in revenue from the show, stands accused of blurring the line between art and commerce, and of making it less likely that small museums will be able to borrow art from big museums.

But when "Claude Monet: Masterworks from the Museum of Fine Arts, Boston," closes on May 30, the relationship between the Boston museum and the Las Vegas hotel's gallery will not close with it.

A new show of Impressionist paintings, again drawn from the Boston museum, is expected to follow the Monet exhibition at the Bellagio Gallery of Fine Art, according to its marketing director, Matthew Hileman. An official for the Museum of Fine Arts, Boston, said that negotiations are ongoing.

Marc Glimcher, president of New York's PaceWildenstein Gallery, which has run the Bellagio Gallery since 2002, said of the Boston museum, "They've had the backlash to the first show, but they've also had the revenue stream." With regard to negotiations for the new show, he said, "we are keeping our fingers seriously crossed."

The Monet show, which opened on Jan. 30, 2004, has drawn an average of 1,000 visitors a day, Mr. Glimcher said. Ticket sales, at $15 per adult, could total $6 million, with the Boston museum receiving a percentage. Museum officials would not say what their financial share is. The museum also receives revenue from sales of Monet prints at the Bellagio Gallery gift shop.

This is hardly the first time an American museum has entered into a moneymaking venture. But instances of museums lending works to profit-making galleries are rare, say experts.

"That's probably where some of the controversy comes from," said Andrea Bundonis, the PaceWildenstein executive in charge of the Las Vegas Gallery. Ms. Bundonis added that she and Mr. Glimcher (who are married) are contractually barred from discussing the financial arrangements with the museum. Newsweek reported last year that the Boston museum was guaranteed $1 million from the show.

"I think it's important to maintain the line between for-profit and not-for-profit," said Selma Holo, a professor of museum studies at the University of Southern California. The standard museum practice of selling books and postcards, she said, "is different from thinking of the collection itself as a way of making money."

Ivan Gaskell, the Margaret S. Winthrop Curator of Paintings, Sculpture and Decorative Arts in the Harvard University Art Museums, said "the system by which museums lend works to other museums at cost could break down" if museums become accustomed to receiving fees for artworks.

The guidelines of the 168-member Association of Art Museum Directors state that "in any decision about a proposed loan from the collection, the intellectual merit and educational benefits must be the primary considerations, rather than possible financial gain."

Officials at the Boston museum, which belongs to the association, say that educating the public is exactly what the Las Vegas show is doing.

Las Vegas doesn't have a major art museum of its own. By sending a group of Monets to the Bellagio, the Boston museum has enlarged the audience for them, said Katie Getchell, the museum's deputy director for curatorial administration.

"I don't think it's very different from what we've done before, lending out shows, except for the type of venue that it's in," Ms. Getchell said.

Mr. Glimcher said "it is important to note that most of the Monets in the show would have been in storage" at the Boston museum during the entire run of the show.

Some 30 percent of the visitors to the Bellagio Gallery, he said, have never been to an art gallery before, according to surveys.

Ms. Getchell noted that in the 1980's, several American museums lent paintings to galleries in Tokyo department stores. She said that when the Boston museum lends individual works to a "sister museum," it usually charges only its costs for packing, shipping and insurance.

But when museums lend entire shows, other arrangements are common, Ms. Getchell said. "It may be just a fee, or it may include a percentage of the ticket sales. Some museums want a percentage of the gift shop and cafeteria revenue, too."

Mr. Gaskell said he is concerned that museums deciding where to send objects will favor institutions that can pay a lot. Small museums, he said, "will be at a disadvantage."

If that happens, museums that have artworks to lend are likely to be in good shape, said Michael Conforti, director of the Sterling and Francine Clark Art Institute in Williamstown, Mass. His own institution is about to mount a show of works by Jacques-Louis David, the French painter, some of them borrowed.

"The only reason why we can do an exhibition like that is because we have trading relationships with other museums," he said. "If you have great works of art, you will be asked to lend them out, and then people will reciprocate."

Museums that do not have valuable pieces to lend - which, he said, are likely to be in newer population centers, like Palm Beach, Fla., Phoenix, and Denver - "may find themselves out of luck," Mr. Conforti said.

But to Mr. Hileman, if the Las Vegas deal is singled out for criticism, it is because Las Vegas is viewed by some as lowbrow, while Boston is seen as a bastion of high culture. "People think a Boston museum is pandering when it does something like this," he said. "Las Vegas is such an easy target."